The first time I stayed at the IC GS in HK I did not have my amb tag and I was ushered to the normal check in line (at the time there were maybe 5-6 people in front of me, and since it was my first time I didn't even know there was a separate amb check in). My second stay at the IC GS (at this point I still didn't know there was a separate amb check in) I had my luggage tags on and I went to wait in the normal line. One of the managers immediately came up to me and ushered me to the amb line (which was a lot shorter). So moral of the story is, put it on your luggage tag or else no one would know if you're an RA, amb, plat member or a normal customer.